Journal of the American Chemical Society, Vol.135, No.8, 2975-2978, 2013
Dynamic Nuclear Polarization Enhanced Natural Abundance O-17 Spectroscopy
We show that natural abundance oxygen-17 NMR of solids could be obtained in minutes at a moderate magnetic field strength by using dynamic nuclear polarization (DNP). Electron spin polarization could be transferred either directly to O-17 spins or indirectly via H-1 spins in inorganic oxides and hydroxides using an oxygen-free solution containing a biradical polarization agent (bTbK). The results open up a powerful method for rapidly acquiring high signal-to-noise ratio solid-state NMR spectra of O-17 nuclear spins and to probe sites on or near the surface, without the need for isotope labeling.